Change in the low-lying Raman scattering spectrum in the glass transition of dehydrated polycrylamide gel

The low-lying Raman scattering spectra were observed in the glass transition of a dehydrated polyacrylamide (PAAm) gel after examination of the transition by the differential scanning calorimeter (DSC) measurement. With increasing temperatures, a marked decrease in the scattering intensity of the Boson peak was observed. However, the peak could be still distinguished at temperatures much higher than the glass transition temperature. This feature could be due to the cross-linking of the polymer chains in the gel.